This invention has relation to tree transplanting machines wherein curved tree digging spoons are mounted in a ring around a tree to be transplanted and are forced and guided down into the ground to completely encompass the tree roots and to separate from the ground the tree roots and a tree ball encompassing those roots which can then be lifted out of the ground and transported to be transplanted in a provided opening at a new location. This is an improvement over my U.S. Pat. No. 4,031,637 for TREE TRANSPLANTING MACHINE granted to me on June 28, 1977, and the complete disclosure of that patent is incorporated herein by this reference to it.
In my patent, I disclosed a mechanism for driving each spoon into the ground. This mechanism included an upright curved stanchion having a rack in parallel spaced relationship to a rack on the upper half of a digging spoon, a pinion operably associated with both racks, and a hydraulic linear motor having its piston rod in driving relationship to the pinion. This provided twice the movement of the spoon into the earth for every unit of movement of the linear motor. This substantially reduced the overall height of the stanchion and motor assembly over the then prior art and allowed the machine to be used to transplant trees with major branches closer to the ground than was otherwise possible.
However, the linear motors still extended above the top of the digging spoons when the spoons were in their uppermost position. A structure whereby the stanchion and linear motor assembly did not extend appreciably above the uppermost position of the digging blades would have been more desirable.
In my patent, the path of the digging blade was guided and determined by a plurality of spaced-apart spoon rack bars 124 welded along a digging spoon rib 126, the rib 126 extending between spaced apart curved flanges 122,122 of the upright stanchion 32, and the rack bars sliding against these flanges 122,122. See FIGS. 7 and 11 of my patent. This metal to metal contact, in guiding the digging spoons into the ground was satisfactory, and my tree transplanting machine made according to this disclosure operated successfully for a number of years. However, there was necessarily a very substantial friction loss due to this metal to metal contact, requiring substantial additional force to be exerted than would otherwise be necessary in driving the spoons into the ground.
As perhaps best seen in FIG. 5 of my patent, the force exerted by the linear motor 38 on the pinion 43 was not in precise parallel alignment between digging spoon rack and the stanchion rack, and this component of force increased the friction between the metal to metal contact referred to above.
For many years, it has been known to force curved blades into the earth around a tree to be moved to isolate root structures and the surrounding earth into a roughly semi-circular tree root ball that can be lifted from the ground and moved to the desired new location and reinserted into a prepared hole in the ground.
In my patent specification, I called attention to patents to Wilkins, U.S. Pat. No. 594,668, granted in Nov. 1897; to U.S. Pat. No. 1,599,841, granted in Sept. 1926; to Wassell et al., U.S. Pat. No. 2,769,278, granted in November 1956; and to Crawford, U.S. Pat. No. 2,990,630, granted in July 1961. These patents were not close enough to be cited by the Examiner in the prosecution of my patent, and it is not believed that they are particularly pertinent to the inventions set out herein.
It is well known to use hydraulic piston-cylinder linear motors to drive digging blades into the ground and to pull them out again. See the patent to Bates, U.S. Pat. No. 3,618,234, granted in November 1971. In some structures of the prior art, in order to gain more power, a reverse ratio has been used whereby the movement of the blades into the ground is only one-half of that of the movement of the power means forcing the blades into the ground. See the patent to Sigler et al., U.S. Pat. No. 3,017,719, granted in January 1962. These patents were cited by the Examiner in the prosecution of my patent.
Other patents cited in my U.S. Pat. No. 4,031,637 include the following:
U.S. Pat. No. 3,017,709, Sigler et al., January, 1962; PA1 U.S. Pat. No. 3,364,601, Korenek, January, 1968; PA1 U.S. Pat. No. 3,460,277, Grover et al., August, 1969; PA1 U.S. Pat. No. 3,558,177, Snead, January, 1971; PA1 U.S. Pat. No. 3,589,039, Korenek, June, 1971; PA1 U.S. Pat. No. 3,713,234, Grover et al., January, 1973; PA1 U.S. Pat. No. 3,936,960, Clegg, February 1976; PA1 U.S. Pat. No. 3,958,613, Herz, May, 1976; PA1 German Pat. No. 23 53 828, granted in October 1973.
None of the above are believed to be as pertinent to the present invention as is my patent itself.
It is known to use a housing to pivotally support a pinion in spaced relation to a backup roller to insure that a rack between the pinion and roller stays firmly engaged with the pinion. See FIGS. 2 and 3 of U.S. Pat. No. 3,142,197 granted to Le Tourneau in July of 1964.
It has been proposed to force digging blades into the ground through the use of worm gears acting on nut assemblies fastened to top ends of such digging blades. See U.S. Pat. No. 4,226,033 to DeHaan, granted in October of 1980 on an application filed Jan. 1, 1979. As best seen in FIG. 5 of that patent, the driving worm gears or "upright lift screws 47" extend substantially above the tops of the guide units 41 and the uppermost position of the digging blades 42. In order to transplant trees having substantial branches lower than the top edges of lift screws 47, it will be necessary to cut off those branches.
Also, in the DeHaan patent, the outermost central edge portion of the digging blades 42 are said to be supported by guide rollers 63 rotatably supported in a mounting frame 64. It is stated that these guide rollers 63 are mounted on sliding bearings 65 "for adjustable movement laterally of blades 42 by adjusting screws 66." See FIG. 8 of DeHaan. At column 4, beginning on line 42, "as shown in FIG. 2, inward lateral movement of a [digging] blade 42 may be limited by the [metal to metal] engagement of the blade with the arcuate edges 44 of the guide unit legs 42." This metal to metal contact greatly increases friction and increases the designed maximum thrust capacity of the digging motors.
The upper end of each digging blade 42 of DeHaan is guided in downward direction by pairs of tracks 46,46 extending integrally inwardly from parallel, spaced-apart side legs 43,43 fixedly and integrally mounted as parts of each guide unit 41. Pairs of rollers 62,62 are rotatably mounted on each connecting member 58 which is integrally connected to a digging blade 42. The rollers 62,62 are confined between the adjacent parallel tracks 46,46 and so determine the downward path of the upper end of the digging blade 42.
This guide structure including bottom roller 63 and upper rollers 62,62 do not positively limit movement of digging blades 42 in direction at right angles to side legs 43,43 of each guide unit 41. Any slight movement of any of the blades 42 normal to their associated guide unit side legs 43,43 results in a misalignment and a mismatch of the lower ends of the blades when they reach the limit of their travel in downward direction, and the overlapping and gaps thus caused results in an unsatisfactory support for the tree ball while it is being lifted and transported.
The structure for guiding the digging blades 42 of DeHaan is such that the only adjustment of the blade path which can be made is in the positioning of the lower guide roller 63 through the use of adjusting screws 66,66 as shown in FIG. 8 of DeHaan. Any wear of the bushings or any warping or other distortion of the digging blades 42 and of the other parts necessitates a long and painful procedure to readjust each pair of adjusting screws 66. Even after that adjustment is made, the path through the earth will never be exactly the same inasmuch as the upper guide path remains fixed while the lower guide point (lower guide roller 63) has been moved. Thus less than a perfect fit of the blades at their lowermost position must necessarily result.
A further difficulty with the worm gear or "lift screw 47" is that it is necessarily open to contamination with dirt falling from the digging blades after a tree has been transplanted and the blades are raised from the ground. This increases the friction losses in the operation of the worm gears and results in an overall increase in the maximum available power necessary to operate the apparatus.
To develop a power drive for tree transplanting spoons which includes a guide path for those spoons which is readily adjustable along its entire length, which can be operated to force digging spoons into the earth without appreciable wasted frictional losses, and which includes structures not appreciably higher than the digging blades themselves at their uppermost position, the present invention was developed.
The inventor and those in privity with him know of no prior art closer than that identified and discussed herein, and know of no prior art which anticipates the claims herein made.